Strange 'drifting' in Cinnamon desktop

[Angelo Graziosi <angelo.g0@libero.it>]

Usually I use Emacs configured with

  (desktop-save-mode 1)

to save the session in a 'desktop' file. I have also something like this

(setq default-frame-alist
      '(
        (width . 115) ; character
        (height . 51) ; lines
        (font . "Monospace-11") ; font
        ))

so that the frame has always the same dimensions.

When the 'desktop' is not yet created, Emacs starts positioning the frame more or less at random. Then I move the frame so that its top-right (T-R) corner overlaps the T-R corner of the screen. Quitting Emacs asks to save the desktop. The next time Emacs starts, the frame occupies the same position with the T-R corner on the T-R of the screen. 

It worked that way on Windows, macOS and GNU/Linux Mint+Mate desktop.

Last year, for various reasons, I had to install GNU/Linux Mint with Cinnamon desktop. Here, with the same configuration, at each start, Emacs drifts a bit toward left and after a while I had to re-positioning it to avoid it overlaps too much the window of other applications.

I tested to the extreme this behavior and found that it stops to drift only when its top-left corner overlaps the top-left corner of the screen.

I wonder if someone has a fix for this when using Cinnamon. I tried to change the Cinnamon configuration but apparently without success.

Thanks,
 Angelo.